Tone-arm construction



March 16 1926.

i C. SCRABIC Tous ARM CONSTRUCTION Filed March 28 `1921 Patented Mar. 16, 1926.

UNITED STATES CARL SCRABIC, OF URBAA, OHIO.

TONE-ARM CONSTRUCTION.

Application filed March 28, 1921. Serial No. 456,046.

related sections capable of supporting ak reproducer or sound box in such manner that the latter may have its position easily and conveniently altered so as to be capable of reproducing both the lateral and hilland-dale type ofrecords, and to permit this object to be accomplished in such man-- ner that direct :metallic contact between.

the joints of the tone arm sect-ions will be precluded. p

Another object of the invention resides in providing a universal joint connection Xbetween the inner and outer sections ofthe tone arm, the said joint allowing for veri tical movement of the outer end Vof the tone arm in order that the reproducer carried thereby may be lifted out of engagement or dropped into reproducing relationship with the grooves of a record, and the said joint being` further formed to include a vertical pivot lwhich will be operative to allow for lateral movement of the reproducer when the latter is reproducing a record, a structure therefore being provided which will serve to maintain the stylus of the sound box in a proper positionv at all times within record grooves, and to enable the instrument to automatically adapt and accommodate itself to irregularities in the curve characteristics of said grooves.

A further object of the invention iesidcs in providing the inner end of the tone arm with an improved pivotal bearing, the latter including a stationarily mounted casing in which the inner end of the tone arm is rotatably received, the said casing and tone arm being provided with spaced sets of horizontally situated anti-friction` bearings, which serve to enable the tone armto swing horizontally, freely and without friction and also to provide an efficient construction for supporting the overhanging outwardly extending portions of the tone arm.

Other objects of the invention reside in a tone arm wherein the above features are present, and also of the structural features which serve toproduce a const-ruction capable of being economically and easily manufactured, to vprovide an efficient conduit for Vtransmitting sound vibrations from a reproducer to an amplifier construction in such manner that the passage of the sound vibration through the tone arm rwill'loe free and unobstructed by outside influences, and to form the various joints of the tone arm so that direct contact between relatively 'movable metallic members will not result in setting up vibration or cxtrnneous metallic chatter.

rlheinvention accordingly consists, in-thev novel features of construction, combinations of elements and arrangements of parte, hereinafter to be fully described and pointed out in the appended claim.

In the aecomj'ianying drawing: Figure l is a vertical transverse sectional view taken through the tone arm comprising the present invention,

` Figure 2 is a transverse vertical sectional view taken along the line 2--2 of Figure l., Figure 3 is a similar' view talren on the plane indicated by th-e lineB--S of Figure i, Figure i is a detail view of the spring employed in the outer joint of said arm, and Figure 5 is a horizontal sectional view taken along the line 5-'5 of Figure i.

-Referring more particularly to the details of the invention, and to the specitic form thereof disclosed in the accompanyingl drawing, the numeral l designates my iinproved tone arm in its entirety. This tone arm is formed from a plurality of continuous, substantially telescopic sections, preferably formed from seamless tubes. which are adapted to be assembled' in a manner to be hereinafter specifically set forth. The tone arm as a whole is pivotally mounted as at 2 in connection with the cabinet 3 of a talking machine, in order th at the outer end of said arm may swing on the usual horizontal plane across the playing surface of a record 4, the latter being adapted to be rotatably and removably carried by the `usual revolving turn table 5,

which may be driven by means of an ordinary motor shaft 6. It Will vbe understood that the reproducer or sound boX 7, carried by theouter end of a/tone arm` 1 will carry the usualA stylus c onstiiicti-onl 81 which` may be arranged for cooperation with the grooves of the record t in a manner customary to apparatus of this character;

The tone arm 1 includes at itsinner end a vertically pivoted elbow section 9*,V which carries at its lower end, a .sleeve .10 of nubf ber, leather or any other non-vibratory niaterial. Arranged tobe rigidly secured in connection with theseetion, 9, and to surround thesleeve 10 is" a metallic sleevev 11 which, in` thisl instance, includes, vertically spaced. horizontallyx extending. collars 12, the.

latter being; adapted to provide. seats for hardened steell` rings, 1B, which are adapted to receive a. plurality of,l anti-frictiondevices 14, in this instance in the form of ball bearings.

The cabinetA 3 is provided .with` a metallic.

easing15, which is ar Tanged to concentrically surround the lowerenzd ot the section i), the said. casing` being. provided. with an.

internal;r chamber. 163 inv which the. sleeve. 11. is rotatably received. The lowerend of, the casing projects through an opening 1.7 formed in the cabinet hand in this` instanceV the casing` is formed with an integral outstanding collar 1,8,- which is adaptedto rest upon the upper. surface ot the cabinet 3 and to be secu-red stationarily to thelatter by means of fasteningl screwsor their equivalents 19. The bottom ot' the casing. is termed with an inwardly directed annular flange 2 0, which provides'. a, seator a` steel,

ring` 21, the lat-ter being arranged for cof operation with the lower-most of, the rin-gs 13 andin combination with the latter provides a racewiayA for, thereception et the lower set; ot ball bearingslet, y It will bey tween the lower end ot the section 9 and the iiangre 2()` and also to prevent outside air currents trein entering the sound conduit by way of' the joints provided between the section 5;) and the casing' The upper end ot the casing'v is threaded as at 24; tovreceive a closure member 25, which also carriesa steel ring`26 for co; operation with the ball bearings provided upon the uppermost ot' the rings 13, and to thus produce a raceway 27 which will be positioned in ,a plane above the raceway 22. It will. be apparent. that when the closure memberis removed thestructmi'e con-. stitutingl the pivotatmounting for thetone arm maybe readily positioned within the chamber 16,V andthen by the application of the,closure-.memben the partswill. be rotatably maintained within the.casing1 andprevented from moving' vertically.-inanv undueI` member upon the casing, it will be manilest that theproper degree of pressure'may be brought to bear upon the bearings let so as to insure their proper positioning within the raceways 22 and 27 and to thus provide fou a freely rotatable tone arm. lt willv be` observed that by reason ot this pivotal construction, the said tone arm will be. capable of, oscillating freely and easily, and therefore but a minimum of 'friction will exist between thev stylus of the tone army and the grooves of the. record during` the moyement .of the tonic` armv across the record, aC feature which results in coi'isiderably diininishing the scratching;- or grating noises which. are ordinarily apparent in ord. reproduction. Also, by spacing the raceways 22 and 27 in the manner. set. torti), it, will `be apparent, that the weight ot the outer overhangingg, end of the tone arm may be readily taken care ot in. such manner that all bindingin the pivotal mounting; will be, eliminated. It .lesired, a vertical web 28 may be provided.betwcenthe collars 12, which willbe capable ot contactingwvitli stationarystops 29, iu order that the swingingmoveincnts ot; the outer cnd'o't the tone arm will, be limited to a-r prescribed art.

The upper end ot the sleeve 1 terminates in an out\.\'ardly directed horizontally extending. portion 30, which is adapted to receive theenlarged: end 31 of a rigid tubular section 32, the end 31. being` secured within the upper end of the section Qin; any suitable manner, such as by ay drawn or a soldered connection so that the sections 9 and 32 willy constitute a rigid unitary part of the tonearm. l

The outer end of. the section B2 has tormedthereona rigidly carried cup shaped member 33, which forms an essential part of a universal joint construction, Sel, which is utilized in articulately connecting the outer and; inner sections of the tone arm. To this end, the member 33 includes vcrtically aligned and extending` trunnions Z55, which receive a ring 3G, and serve to confine the latter within-thecup 33 so thatv the ring will,bepermittcd to swingen the rei tical pivots afforded by said trimnimis. lt will be observed that the outer face oi the ring is of curved formation in order that the saine will be permitted. to swing about the trunnions. without interference on the partv of the inner wall of the cup4 member.

The ring 3G is, inV turn, provided with horizontally situated pivot pins 37, which have their, pointed endsarranged to be positioned within aligned` depressions provided upon opposite sidesofasubstantially spherical head 38,*whichis rigidly carried upon the inner end offa pivotedl tubesection Preferablya rubber .orother similar sleeve Ll0 isfrpositioned between the head 38 and the end of thetube section 39, in order that direct contact between metallic parts will be eliminated. Similarly, an enlarged gasket Lll is seated vertically within one end of the cup member 33, and is arranged between the outer end of the section 32, itscup member 33 and the ring 36 and spherical head 33. This gasket prevents direct contact between relatively movable metallic parts but serves more essentially in sealing the sound passage between the sections 32 and 39, so that outside atmospheric disturbances will not .be permitted to enter the conduit. By reason of the-universal joint, it will be apparent that the sound box 7 carried upon the outer end of the tone arm may be dropped upon or lifted from a record by swinging the outer end of the tone arm about the pivotal axis defined by the pins 37, the spherical formation Vof the head 33 permitting of such relative movement on the part of the section 39 with respect to the ringl 3G. In this instance, the head 33 or its equivalent is adapted to be provided with a stop shoulder 42, which is capable of engaging with one edge of the ring 36 'to limit downward movement on the part of the sound box. Then, by reason of the provision of the vertical trunnions the sound box will be capable of having an independent horizontal swinging movement with respect to the main swinging movement of the sections 9 and 32 of the tone arm. rhis supplemental swinging movement is provided in order that the outer end of the tone arm and the reproducer may be adapted to follow irregularities in the record construetion. However, by use of the compound pivotal joint 34, the sound box will be permitted to move laterally and vertically so that the stylus 8 thereof may be properly maintained within the grooves of a record, that is, the stylus or needle will have its lower extremity atall times centrally positioned within a record groove and to thus avoid undue frictional contact between the stylus and the walls of a groove. While the outer end of the tone arm will be permitted to swing a slight dist-ance about the vertical pivots 35, yet by the provision. of the gasket 4l, undue swinging movement will be precluded and the tube sections 32 and 39 normally maintained in longitudinal a l ignment. I

'lhc outer end of the tube section 39 is ','lexibly connected with the cxtreme outer section a3 of the tone arm. by means of a novel and improved joint 411-, the function of which joint being to enable the sound box T to be adjusted so as to be capable of reproducing both lateral and hill-and-dale cut records. To this end, the outer portion of the tubular section 39 is downwardly and angularly inclined as at Ll5 with respect to the longitudinally extending portions of said section. 'lhe inclined portion Ll5 terminates in a relatively enlarged bell shaped mouth 4G in which is rotatably received the inner and upwardly incli ed angularly extending end 47 of the section 43, the axis of the portions 415 and l? being coincident. The mouth s'l-t includes a ga'let -i-S, which is seated betwen adjacent walls of the portions l5 and 4l? and acts to prevent direct Vcontact of the n'iovable metallic parts, and yet permits of free rotation of the end et? relative to the section 43. To control the exrent of this rotation, the end Ll? is provided with diametricallv disposed rigidly projecting studs a9, which are arranged so that their outer ends will be received within an arcuate slot :59 provided vin th-ewall of the inclined portion 4:5. The slot 59 is of substantially 90 in length, in order that when the sound box.

being adjusted from one operative position'to another, the contacting of the stud 49 with the end walls of the slot 59 will serve to insure a proper positioning of the sound box. lt will be understood that the said sound box is adapted to be 'carried by the outer end of the section 43, and that when in th-e position shown in Figure l. the same will be adapted for use in repro-V ducing lateral cut records, however. by swinging the section a3. the outer end of the latter n'iay be caused to assmne a position capable of permitting the sound box to reproduce hill-and-dale records. To maintain the sections 39 and in their positions of relative adjustment, the angular Vend ai" is provided with a collar 5l, which is adapted to be received within the mouth a6, and arranged to be positioned between the inner wall of the collar'and an annular shoulder 52 is a spring washer 53, the said washer normally serving or tending to force the section 43 away from the outer end of the section 39, this movement, however. being counteraoted by the studs 49. It will be observed that the ends of the slot are formed with notches 54. which are so located that when' the sound box has been properly adjusted the spring 53 will serve llU to force the studs -l9 into one or the other of said notches and to thus lock the sections 39 and 43 together. It will be under-` stood that the reproducer 1' may be secured in any approved manner to the outer end of the section a3.

In view of the foregoing description, taken in conjunction with the accompanying drawing, it will be apparent that the present invention provides a. tone arm wherein is to be found many improved feaf tures of improvedA construction. In this respect, it will be observed that by the provision of the compound joint 34 the rcproducer, connected with the tone arm, is capable of being properly maintained and centered in conjunction with the groove of u record und tonntonint-icnllyl nveeoinnimlute itselt to the irregularities, more ou lese` Slight und noticeniiile, which nre present in ull records. SecondlyE an. improved joint is provided in the outerl sections of the arm `tor enabling' the sound box to be propeiflv adjusted for various.; types ot'. reeordn, und to be positivelyY maintained in such adjustment in un el'lioient, een ie-nient and effective mnner. Thirdlyj a tone erm is provided including nrtirnlzitely related. sections which nre :so formed und. united that relatively niorul'ile nietnllie pnrts will he maintained out ot physical Contacty und to thus reduce or eliminate undue nietullie rilrirzition in the ton-e nrin. Fourth, the joint construeions are such tint the interior of the tone nrni or the Sound conduit theretlnoughy is Sealed eo that extraneous atmospheric dist-urbames will be prevented from entering;

the sound Conduit und. disturbine` the sound Yilnntions roperl v eet up thereiin und' finally, nn improved Construction is provided 'l'or otlectinn'` the pivotal Support ol the tone. erin as n Whole in order thet the lutter may oseillate freely und ithout undue Yfriction nerosS` thev pl ying surliucervoi n neem-.th und to. compensate for the rela.- tivelfy heavy oilset or, cmerluinging outer end ot' thetoneinrln, sothnt tl'ievweight ot' such end will not interfere'with the pivotal more nient of the tone nrm about its inuin vertical axis.

vWhat is claimed is:

In a. tone nrn1 connnnnioating inner und outer seetionsv a; Compound pir-etal connexition; between said sections consistingy ot :i ring' arranged to be. received within the outer end 0i theiuner Sett-ion, vertical trunnione between Said ring und the outer end ot the inner sect-ion. u eurfved enlurgeinent iirfniclod upon the inner end o'lithe outer Sect-ion, honi'fiontnl trunnions uniting Fnjd enlargement withL seid ring, undA u gasket formed 'trein a colnpreseihle materiali and Situated; between, Suidy ring` und the outer end ot said inner sect-ion, s uid gasket serving to nieintain Suid; ring-in a, no1-.mul position und to seal the Conduit prioridad lu: said Sect-ions.

ln teetimon;v whereof aiiix my Sigfnjf'ature.

CARL SCi/RA BIC. 

